Cell Biology and
Cancer
What is cancer?
• In simple terms, cancer is a group of more than
100 diseases that develop across time and
involve the uncontrolled division of the body’s
cells.
• Cancer begins when a cell breaks free from the
normal restraints on cell division and begins to
follow its own agenda for proliferation
(multiply).
What is a tumor?
• A tumor is a mass of cells.
• In situ cancer- means the abnormal cells
remain within the tissue in which it
originated.
• Invasive cancer- when the abnormal cells
begin to invade nearby tissues.
Malignant
• An invasive tumor is said to be malignant.
The cells shed in to the blood or lymph
from a malignant tumor.
• This likely establishes new tumors
throughout the body, also known as
metastases.
• Tumors threaten an individual's life when
the growth disrupts the tissues and organs.
3 stages of tumor development
Cell with genetic mutation, hyperplasia,
dysplasia, in situ cancer, invasive cancer.
Research
• Over the last 3 decades, research has
revolutionized our understanding of cancer.
• Largely due to the application of the techniques
of molecular biology.
• Today we know cancer is a disease of molecules
and genes
• Our increasing understanding of these genes
makes it possible for development of new
strategies for preventing, forestalling and even
correcting the changes that lead to cancer.
Clues from epidemiology
• In 1775, a high incidence of scrotal cancer was
described among men who worked as chimney
sweepers.
• In the mid-1800’s, lung cancer was observed at
alarmingly high rates among miners in Germany.
• At the end of the 19th century, using snuff and
cigars was thought to be closely associated with
cancers of the mouth and throat.
• These observations and others suggested that
the origin or causes of cancer may lie outside the
body, and more importantly, they could be
linked to identifiable and even preventable
causes.
• These ideas led to a widespread search for
agents that might cause cancer.
• An early notion, prompted by the discovery that
bacteria caused a variety of human diseases,
suggested cancer was an infectious disease.
• Another idea was that cancer arises from
chronic irritation of tissues.
• This view received strong support with the
discovery of X-rays in 1895 and the observation
that exposure to this form of radiation could
induce localized tissue damage, which could lead
in turn to the development of cancer.
• Another view is that it is hereditary.
• In 1910, a submicroscopic agent was
isolated from a chicken tumor and found
that it could induce new tumors in healthy
chickens.
• This theory led scientists to find out that
an agent known as the Rous Sarcoma virus
is one of several viruses that can act as a
causative factor in the development of
cancer.
Clues from cell biology
• Cancer cells are indigenous cells—abnormal
cells that arise from the body’s normal tissues.
• All malignant tumors are monoclonal in origin
(cells are derived from a single clone).
Development of cancer
• The development of cancer occurs as a result of
a series of clonal expansions from a single
ancestral cell.
• Although a tumor is monoclonal, it may contain
a large number of cells with diverse
characteristics.
Normal cells vs. cancerous cells
• Cancerous cells look and act differently from
normal cells.
• In normal cells, the nucleus is only 1/5th the size
of the cell.
• In cancerous cells, the nucleus may occupy most
of the cells volume.
• Tumor cells have lost their restraints on growth
that characterize normal cells.
Cancer Trends Progress Report
(CTPR) - 2007 Update
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MeasureTrendPREVENTION
Age at smoking initiationStable
Youth smokingFalling
Adult smokingFalling
Quitting smokingStable
Health professional advice to quit smokingFalling
Secondhand smokeEnvironmental Tobacco Smoke NSC
Smoke-free work environment Rising
Smoke-free indoor air lawsRising
Fruit & vegetable consumptionNSC
Red meat consumption Stable
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Fat consumption Stable
Alcohol consumptionRising
Weight (both sexes) Healthy weightNSC
OverweightStable
ObeseNSC
No leisure time physical activityNSC
Sun protectionFalling
Pesticide levels in the bloodRising
Dioxin levels in the human bodyFalling
EARLY DETECTION
• Breast cancer screeningFalling
• Cervical cancer screeningFalling
• Colorectal cancer screeningFecal Occult Blood
Test (FOBT)Falling
• EndoscopyRising
• Colorectal test useRising
DIAGNOSIS
Incidence
• All cancersFalling
• WhiteFalling
• BlackFalling
• HispanicsFalling
• American Indian/Alaskan NativesNSC
• Asian/Pacific IslandersFalling
Four most common cancers
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ProstateStable
Female breastFalling
ColorectalFalling
Lung and bronchusFalling
Cancers that are increasing
• Non-Hodgkin lymphomaRising
• Melanoma of skin (White only)Rising
Stage at diagnosis
ColonFalling
Female breastStable
RectumFalling
CervixNSC
ProstateFalling
Breast cancer treatment
• MastectomyFalling
• No surgeryRising
• BCS with radiationNSC
• BCS without radiationRising
• Multiagent chemotherapyRising
Colorectal cancer treatmentRising
Life after cancer
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Survival:
All cancersRising
ProstateRising
Female breastRising
ColorectalRising
Lung and bronchusRising
End of life (all cancers)
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All cancersFalling
WhiteFalling
BlackFalling
HispanicFalling
American Indian/Alaskan NativesStable
Asian/Pacific IslanderFalling
Mortality of the 4 main cancers
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ProstateFalling
Female breastFalling
ColorectalFalling
Lung and bronchusFalling